1. Field of the Invention
The present invention relates to a wireless data communication system. More particularly, the present invention is directed to a system for connecting one or more mobile communication devices directly to a data network via a wireless telecommunication network.
2. Description of the Related Art
Developments in wireless communication technologies have made mobile communication devices, such as cellular telephones, relatively inexpensive and reliable. At the same time, portable computers, some small enough to fit in a user's pocket, have gained widespread use. As a result, wireless data communication through a wireless telecommunication network has become possible by providing a portable computer with a modem and connecting it to a mobile communication device. Thus, portable computers equipped for wireless data communication could be used to remotely connect a user to a data network, such as the Internet, from any location within the wireless telecommunication network coverage area.
Typically, wireless connection to a data network is accomplished as follows. When a data call is placed from a mobile communication system, which includes a portable computer, a modem and a mobile communication device, the mobile communication system connects to a base station through the wireless telecommunication network. The base station is typically a telecommunication system capable of routing a call made from a mobile communication device within a predetermined range to another mobile communication device also within range, to another base station for rerouting to a distant mobile communication device outside of the range, or to a standard telephone on a wire or "land" line that is part of the Public Switched Telephone Network ("PSTN"). The base station routes the data call received from the mobile communication device to a data network gateway through the PSTN. The data network gateway is commonly a hybrid computer and telecommunication system that enables individual users to connect to a data network, such as the Internet, via a number of high speed digital data communication lines. Data network gateways are typically operated by data service providers, who for a periodic subscription fee grant to the users the right to access a data network through the data network gateway. Assuming that the user has access rights to use the particular data network gateway, the data call received from the base station is connected to the data network. For the duration of the connection of the data call the user may interact with the data network via the mobile communication system. For example, the user can send and receive electronic mail, and upload/download both text (ASCII) and/or binary data files to and from other computers connected to the data network.
The current data network access arrangement is flawed in a number of ways. First, as a mostly analog network, PSTN has limited bandwidth, and suffers from a relatively large amount of signal noise due to the constant transmission and presence of analog voice calls and the varied condition of the wring and switching equipment. Data calls transmitted through the PSTN frequently compete for bandwidth with each other and with analog voice calls. As a result, the PSTN acts as a bottleneck in that increased data communication traffic causes a proportional decrease in data communication speed. Furthermore, data calls are also affected by signal noise, often forcing the mobile communication systems to retransmit lost or corrupted data and resulting in a significant slowdown of data communication.
Second, the PSTN requires a dedicated channel (i.e., a standard voice telephone line) for each data connection. This channel consumes its full bandwidth even if no data is being transmitted, and as a result the PSTN bandwidth is wasted by inactive channels. Moreover, the bandwidth of each data connection is limited by the bandwidth of a voice telephone line.
Finally, as wireless communication technology moves toward a purely digital wireless communication standard, it becomes cumbersome and counterproductive to convert digital data communication from a mobile communication system to analog data for the sole purpose of transmission through the PSTN, and then have to convert the data back to digital form at the data network gateway.
It would thus be desirable to provide a system for connecting a mobile communication system to a data network directly, bypassing the PSTN.